Checks a list of sites for SSL expiration and texts you.

ssl-checker.sh

#!/bin/bash

#Reads a text file -- domains.txt -- containing one domain per line and checks to see if the ssl cert is expiring in the next 30 days

#Config varaiables, 
#days is the number of days you'll get an alert for, 
#phone number 
#api key from https://textbelt.com/ 
days=30
phone="##########"
apikey="###"

# Doing this just to make sure the file is in unix format
dos2unix -n domains.txt temporary_unix_ended_file.txt > /dev/null 2>&1   

# Check if the last character of the file is a newline
if [ "$(tail -c1 temporary_unix_ended_file.txt)" != "" ]
then
    # If not, append a newline
    echo "" >> temporary_unix_ended_file.txt
fi

domains=""
while read domain; do
    expiry_date=$( echo | openssl s_client -servername $domain -connect $domain:443 2>/dev/null | openssl x509 -noout -enddate | cut -d "=" -f 2 )
    expiry_date_seconds=$(date -d "$expiry_date" +%s)
    current_date_seconds=$(date +%s)
    # Calculate the difference in seconds
    diff_seconds=$(( $expiry_date_seconds - $current_date_seconds ))

    echo "$domain - $expiry_date"

    # If the difference is less than 30 days
    if [ -n "$diff_seconds" ] && [ $diff_seconds -lt $(($days*24*60*60)) ]; then
        echo "  Warning: SSL certificate for $domain expires in less than $days days!"  
        domains="$domains$domain, "
    fi
done <temporary_unix_ended_file.txt
rm temporary_unix_ended_file.txt

if [ -n "$domains" ]; then
    curl -X POST https://textbelt.com/text --data-urlencode phone=$phone --data-urlencode message="SSL Warning! $domains expire in under $days days." -d key=$apikey
fi